Boom assembly

ABSTRACT

An extendable boom assembly includes a plurality of longitudinally extending guide walls which define channels for receiving loops or bends in flexible conduits. Upon extension of the boom assembly, the loops move outwardly along the channels into engagement with rollers of a biasing assembly. The biasing assembly tensions the flexible conduits during continued extension of the boom assembly. The biasing assembly also initiates inward movement of the loops along the channels in a predetermined manner when the boom assembly is retracted. Structural frame members of the boom assembly are connected with the flexible conduits and conduct fluid under pressure from the flexible conduits to a device mounted on an outer end portion of the boom assembly.

I United States Patent 1 3,666,125 Gano et al. 1 May 30, 1972 [5 BOOMASSEMBLY 3,214,033 10/1965 Nilsson ..214/010. 11 [72] Inventors: :Zf i gg Schlafly both of Primary Examiner-Robert G. Sheridan ew la ep 10Assistant Examiner.lerold M. Forsberg [73] Assignee: The Warner & SwaseyCompany, Cleve- Attorney-hunt and li land, Ohio [57] ABSTRACT [22]Filed: Sept. 10, 1970 Appl. No.: 70,954

An extendable boom assembly includes a plurality of longitudinallyextending guide walls which define channels for receiving loops or bendsin flexible conduits. Upon extension of the boom assembly, the loopsmove outwardly along the channels into engagement with rollers of abiasing assembly. The biasing assembly tensions the flexible conduitsduring continued extension of the boom assembly. The biasing assemblyalso initiates inward movement of the loops along the channels in apredetermined manner when the boom assembly is retracted. Structuralframe members of the boom assembly are connected with the flexibleconduits and conduct fluid under pressure from the flexible conduits toa device mounted on an outer end portion of the boom assembly.

16 Claims, 9 Drawing Figures PATENIEDMMO I972 668, l 25 sum 10F 3 PAULW/L/AM \SCHZAFLY JOHN W GA/VO ATTORNEYS PATENTEDMAY 30 I972 SHEET 2 BF 3JOf/A/ W GANG BOOM ASSEMBLY This invention relates generally to anextendable boom assembly, and more particularly, to a new and improvedsystem for supplying power to an apparatus mounted on the boom assembly.

A known boom assembly includes inner and outer boom sections which aremounted in a telescopic relationship with each other. Relatively long,flexible hoses are utilized to supply fluid under pressure to anapparatus for operating a tool on the outer section of the boomassembly. When the boom assembly is extended and retracted, these longhoses may be flexed or moved sidewardly so that they rub against thesections of the boom assembly and become worn or abraded. In fact, theflexible hoses may move to such an extent relative to the boom sectionsthat they are kinked or pinched between the boom sections.

Of course, the operating life of the flexible hoses is decreased by anyabrading, kinking or pinching of the hoses which may occur as the boomassembly is extended or retracted. Replacement of these hoses can be arelatively difficult and time consuming task. The difficulty encounteredin replacing the hoses is increased if the hoses are located within thesections of the boom assembly where they are protected againstengagement with external objects.

Accordingly, it is an object of this invention to provide a new andimproved boom assembly wherein flexible conduits for conducting powerbetween movable sections of the boom assembly are protected by a guidearrangement which maintains the flexible conduits in a predeterminedrelationship with the sections of the boom assembly as it is extendedand retracted.

Another object of this invention is to provide a new and improved boomassembly which includes a guide arrangement for guiding movement of aflexible loop formed in a conduit along a predetermined path and abiasing means for applying a biasing force to the loop as it is movedalong at least a portion of this path during relative movement betweensections of the boom assembly.

Another object of this invention is to provide a new and improved boomassembly which includes a plurality of sections which are movablerelative to each other, an apparatus mounted on one of the boom sectionsbeing supplied with energy conducted through a flexible conduit having aloop formed therein in such a manner that the loop is displaced alongthe flexible conduit upon relative movement between the boom section,and wherein the loop moves along a channel formed by a guide arrangementas the boom sections are moved relative to each other, the loop beingengaged by a biasing assembly to tension the flexible conduit and tourge the loop in a predetermined direction along the channel during atleast a portion of the relative movement between the boom sections.

Another object of this invention is to provide a new and improved boomassembly having a pair of relatively movable sections with a conduitmeans for conducting energy to an apparatus on one of the sections, thisconduit means includes a flexible portion having a loop formed thereinbetween an outer leg which is connected with one of the boom sectionsand an inner leg which is connected with the other boom section andwherein the boom assembly includes a biasing means which is operable totension at least the inner leg of the flexible conduit means to maintainit in a predetermined relationship relative to the boom sections whenthe inner leg is relatively long, this biasing means being ineffectiveto apply a force to the loop when the inner leg is relatively short.

Another object of the present invention is to provide a new and improvedboom assembly having a section which is movable relative to a base and afluid operated device which is supported on the boom section and isconnected in fluid communication with a source of fluid on the base by afluid conduit means and wherein this fluid conduit means includes ahollow structural member of the boom section.

These and other objects and features of the invention will become moreapparent upon a consideration of the following description taken inconnection with the accompanying drawings where:

FIG. 1 is a general illustration of a vehicle having a boom assemblyconstructed in accordance with the present invention;

FIG. 2 is a fragmentary elevational view depicting the relationshipbetween inner and outer boom sections and a cradle or base for mountingthese boom sections on the vehicle of FIG. 1;

FIG. 3 is a sectional view, taken generally along the line 3- 3 of FIG.2, further illustrating the relationship between the inner and outerboom sections;

FIG. 4 is a sectional view, taken generally along the line 4- 4 of FIG.2, illustrating the relationship between a hose trough for receivingflexible conduits and the boom sections;

FIG. 5 is a schematic sectional view, illustrating the relationshipbetween one of the flexible conduits and the boom sections when the boomassembly of FIG. 1 is in a retracted condition;

FIG. 6 is a sectional view, generally similar to FIG. 5, illustratingthe relationship between the flexible conduit and the boom sections whenthe boom assembly is partially extended and the flexible conduit isengaged by a biasing assembly;

FIG. 7 is a schematic sectional view, generally similar to FIG. 6,illustrating the boom assembly in an extended condition in which thebiasing assembly applies a tensioning force to the flexible conduit;

FIG. 8 is a schematic illustration depicting the relationship between anapparatus for operating a tool and the inner boom section; and

FIG. 9 is an enlarged illustration of the hose trough of FIG. 4.

The present invention provides a new and improved boom assembly having aconduit positioning apparatus for maintaining flexible conduits in apredetermined relationship with telescopically disposed boom sections toprevent the flexible conduit from being abraded, kinked or pinchedduring relative movement between the boom sections. Although a boomassembly 10 constructed in accordance with the present invention can beused in many different environments, the boom assembly is illustrated inFIG. 1 in association with a vehicle 12. The vehicle 12 includes arotatable platform 14 which supports the boom assembly 10 for rotationalmovement relative to a frame 16 of the vehicle.

When the vehicle 12 is being driven over-the-road to a work location, anoperator drives the vehicle from a cab 20 mounted on a forward portionof the frame 16. Once the vehicle 12 has been driven to a work location,the operator controls the boom assembly 10 from an operators cab 22 onthe rotatable platform 14. An engine 24 is mounted on the rotatableplatform 14 and, in the illustrated embodiment of the invention, drivesa pump (not shown) to provide hydraulic fluid under pressure to effectoperation of the boom assembly 10.

The boom assembly 10 includes inner and outer sections 28 and 30 (seeFIGS. 2 and 3) which are disposed in a telescopic relationship with eachother. The outer boom section 30 is mounted on a cradle or sleeve member34 which is pivotally connected at 36 (FIG. 2) with the platform 14 ofthe vehicle 12. The cradle or base 34 is pivoted relative to theplatfonn 14 by extending and retracting a piston and cylinder assembly40 to thereby enable work operations to be performed in the mannerdisclosed in US. Pat. No. 3,329,291 to Przybylski. Of course, othermounting arrangements could be utilized to mount the boom assembly 10 ona base other than the vehicle 12.

The boom assembly 10 is extended and retracted by effecting relativemovement between the telescopically disposed inner and outer boomsections 28 and 30. Accordingly, a piston and cylinder assembly 38 (seeFIGS. 5 through 7) is extendable to move the inner boom section 28axially outwardly relative to the outer boom section 30 to therebyextend the boom assembly 10. Similarly, the piston and cylinder assembly38 is retractable to move the inner boom section 28 inwardly from theextended position of FIG. 7 to the retracted position of FIG. 5. Theinner boom section 28 is supported for this movement relative to theouter boom section 30 by inner rollers 42 which are rotatably mounted onthe inner boom section 28 (FIG. 4) and are disposed in rollingengagement with longitudinally extending frame members 46 of the outerboom section 30. The inner boom section 28 is further supported by outerrollers 48 (FIG. 8) which are rotatably mounted on an outer end portionof the outer boom section 30 and are disposed in rolling engagement withtubular frame members 50 of the inner boom section.

The piston and cylinder assembly 38 is extended and retracted under theinfluence of hydraulic fluid supplied by a pump (not shown) driven bythe motor 24. This fluid is conducted under pressure through conduits 54mounted on the cradle 34 (FIG. 2) to a hollow piston rod 58 of thepiston and cylinder assembly 38 (see FIGS. 4-7). The hydraulic fluid isthen conducted to a cylinder 60 of the piston and cylinder assembly 38to extend and retract the boom assembly 10 in a known manner.

' A suitable tool 64 is mounted on an outer end portion of the innerboom section 28 (see FIG. 8). A power apparatus or device 66 is mountedon the inner boom section 28 and is operable to efiect pivotal movementof the tool 64 about a connection 68. In the illustrated embodiment ofthe invention, the power device 66 includes a fluid motor or piston andcylinder assembly 70. The piston and cylinder assembly 70 is extendedunder the influence of high pressure hydraulic fluid to actuate alinkage 72 and pivot the tool 64 in a clockwise direction as viewed inFIG. 8. Similarly, the piston and cylinder assembly 70 is retracted topivot the tool 64 in a counterclockwise direction. Although the powerapparatus or device 66 is operated by hydraulic fluid under pressure, itis contemplated that high pressure air or other fluid could be utilizedto operate other types of power devices associated with the tool 64. Infact, the power apparatus 66 could, if desired, include an electricmotor for operating a too] similar to the tool 64.

Hydraulic fluid is conducted under pressure from a pump mounted on theplatform 14 to the power apparatus 66 by a fluid conduit arrangement 74.The fluid conduit arrangement 74 includes a pair of conduits 76 whichare mounted on the cradle 34 (see FIG. 2). The conduits 76 extendthrough opposite side portions of the cradle (see FIG. 3) to a hosetrough 80 mounted on the cradle 34 and outer boom section 30 (one of theconduits 76 being shown in FIG. through 7). A pair of flexible conduits84 and 86 (see FIGS. 4 and 9) are associated with the hose trough 80 andconnect the conduits 76 on the outer boom section 30 in fluidcommunication with conduits on the inner boom section 28. The conduitson the inner boom section 28 include a pair of the hollow frame members50 which conduct fluid to hoses 90 and 92 connected with the piston andcylinder assembly 66 (see FIG. 8).

The hoses 84 and 86 are flexible to enable fluid under pressure to beconducted between the relatively movable boom sections 28 and 30. Thus,the hose 84 (FIG. 5) includes a loop or bend 96 which connects an outerleg or section 98 of the hose in fluid communication with an inner leg100 of the hose. The outer leg 98 of the hose 84 is connected to theouter boom section 30 while the inner leg 100 is connected with theinner boom section 28. Therefore, when the boom assembly is extended orretracted, the loop 96 moves along the flexible hose 84 at a speed whichis approximately half the speed of relative movement between the boomsections 28 and 30.

When the boom assembly 10 is in the retracted condition shown in FIG. 5the loop 96 is located adjacent to an inner end of the hose trough 80.At this time the outer leg 98 of the hose 84 is substantially longerthan the inner leg 100 of the hose. As the boom assembly 10 is extendedand the inner boom section 28 is moved outwardly relative to the outerboom section 30, the loop 96 moves outwardly along the hose trough 80(FIG. 6). Of course this increases the length of the inner leg 100 ofthe hose 84 and decreases the length of the outer leg 98 of the hose.When the boom assembly 10 is fully extended (FIG. 7),

the loop 96 is disposed adjacent to an outer end of the hose trough andthe inner leg of the hose 84 is much longer than the outer leg 98 of thehose.

Similarly, when the boom assembly 10 is retracted the loop 96 movesinwardly from the position shown in FIG. 7 to the position shown in FIG.5. During this movement, the outer leg 98 of the hose 84 decreases inlength as the length of the inner leg 100 of the hose decreases. Whilethe movement of the loop 96 for only the hose 84 has been illustrated,it should be understood that a similar loop is provided in the hose 86and that this loop moves in the same manner as does the loop 96.

If the hose 84 is unrestrained as the loop 96 moves along the hosetrough 80, the hose would tend to whip or flex sidewardly duringextension and retraction of the boom assembly 10. Any tendency for thehose 84 to whip or move sidewardly becomes accentuated when the innerleg 100 of the hose is relatively long. Whipping or sideward movement ofthe hose 84 tends to abrade the hose and could even result in the hosebeing kinked or pinched. When the hose 84 is abraded, pinched or kinked,its service life is greatly reduced so that the hose must be replaced atrelatively frequent intervals. Of course, the hose 86 is subjected tooperating conditions similar to those experienced by the hose 84 andwill have a similar service life.

Replacement of the hoses 84 and 86 is particularly difficult since theyare located between the inner and outer boom sections 28 and 30 and arerelatively inaccessible. This relatively inaccessible location for thehoses 84 and 86 is advantageous since the hoses are protected againstbeing snagged or otherwise damaged by engagement with external objectsduring operation of the boom assembly 10.

A flexible conduit positioning assembly 101 is provided in the hosetrough 80 to position the hoses 84 and 86 relative to the boom sections28 and 30 to prevent undue wearing of the hoses as the boom assembly 10is extended and retracted. The positioning assembly 101 includes a guidearrangement 102 for positioning the loops in the hoses 84 and 86 as theloops move along the hose trough 80 and a biasing assembly 103 fortensioning the hoses. The guide arrangement 102 includes a plurality oflongitudinally extending guide walls 104, 105, l 06, 107 and 108 (FIG.9) which define channels 109, 110, 111 and 1 12 along which loops inflexible conduits associated with the hose trough 80 can move duringrelative movement between the boom sections 28 and 30. While only thehoses 84 and 86 have been shown in channels 1 10 and 111, it should beunderstood that conduits may be provided in the channels 109 and 112 toconduct fluid or electrical energy to associated devices.

The outer leg 98 of the hose 84 is disposed in the channel 1 10 betweenthe guide walls and 106 and rests against an outer wall 116 of the hosetrough 80. The loop 96 extends out of the channel 1 10 away from theouter leg 98 to the inner leg 100 of the hose 84. When the boom assembly10 is extended, the loop 96 rolls along the channel from the positionshown in FIG. 5 through the position shown in FIG. 6 to the positionshown in FIG. 7. During this movement, rounded guides 120 on the innerportions of the walls 105 and 106 engage the sides of the loop 96. Theguides 120 are spaced apart by a distance which is slightly greater thanthe external diameter of the hose 84 to prevent the loop 96 fromwhipping or moving transversely relative to the boom sections 28 and 30as the loop moves along the channel 110 formed between the parallelguide walls 105 and 106. The guides have relatively smooth roundedsurfaces which tend to minimize abrasion on the loop 96 as it rollsalong the channel 1 10 during extension or retraction of the boomassembly 10. Of course, a loop similar to the loop 96 is formed in thehose 86 and this loop rolls along the channel 1 I 1 in the same manneras in which the loop 96 rolls along the channel 110 during extension andretraction of the boom assembly 10.

As the boom assembly 10 is extended from the retracted position of FIG.5 toward the extended position of FIG. 7, the length of the inner leg100 of the flexible conduit or hose 84 increases. As its lengthincreases, the inner leg 100 would tend to whip or move sidewardly if itwere unrestrained. In fact, upon initiation of retraction of the boomassembly 10, the leg 100 is so long that it might tend to cause the loop96 to roll out of the channel 1 or to form a second loop in the hose.

The biasing assembly 103 is associated with the guide arrangement 102 toprevent the flexible conduits in the hose trough 80 from whipping ormoving sidewardly relative to their associated channels when the innerlegs of these flexible conduits are relatively long. The biasingassembly 103 tensions the conduit 84 so that the loop 96 moves or rollsalong the channel 110 in a predetermined manner and is not whipped ormoved out of the channel under the influence of the relatively longinner leg portion 100. The biasing assembly 103 includes a plurality ofrollers 134 which are disposed in the hose trough 80 between the guidewalls 104 to 108. One of the rollers 134 is disposed in the channel 1 10and engages the loop 96 to thereby tension the hose 84 (see FIGS. 6 and7). Similarly, a roller 134 is provided in the channel 1 11 to engage aloop in the hose 86.

The rollers 134 are mounted on a common axle 136 which extends throughslots formed in the guide walls 104 to 108. These slots extendlongitudinally along the guide walls 104 to 108 in a direction parallelto the longitudinal axes of the boom sections 28 and 30. The rollers 134are pressed or urged against the loops in the conduits associated withthe channels 109 to 112 under the influence of a pair of springs 142 and144. The springs 142 and 144 are connected at their outer ends to theaxle 136 (FIG. 9) and at their inner ends to an inner end of the boomsection 30 (FIG. 5). The slots in the guide walls 104 to 108 support anddirect movement of the axle 136 to maintain the rollers 134 in a desiredrelationship with the channels 109 to 112 as the boom assembly 10 isextended and retracted.

When the inner leg 100 of the loop 84 is relatively short, the stiffnessor resistance of the hose 84 to sideward flexing is sufficient tomaintain the hose in the channel 110. Therefore, the biasing assembly103 can be rendered ineffective to tension the hose 84 when the lengthof the inner leg 100 is such that the loop 96 will continue to rollalong the channel 110 independently of any tension in the hose.Accordingly, the slots in the guide walls 104 to 108 terminate near themidpoint of the hose trough 80 (see FIG. 5). Therefore, when the boomassembly 10 is partially retracted the axle 136 engages arcuate end orstop surfaces formed in the slots to limit inward movement of therollers 134. The loop 96 then moves away from the associated roller 134and continues to roll inwardly along the channel 110. Since the rollers134 can not move throughout the entire length of the hose trough 80, thesprings 142 and 144 are shorter, when the boom assembly 10 is retracted,than the length of the hose trough 80 and can be extended to a lengthwhich is almost the same as the length of the hose trough when the boomassembly 10 is extended. This enables the springs 142 and 144 to belocated within the hose trough in a relatively compact arrangement inwhich the springs are protected against engagement with external ob-)ects.

When the boom assembly 10 is operated from the retracted condition ofFIG. 5 toward the extended condition of FIG. 7, the loop 96 rolls alongthe channel 110 toward the associated roller 134 which is locatedbetween the parallel guide walls 105 and 106. When the boom assembly isextended somewhat more than half way, the loop 96 is brought intoengagement with the roller 134. At this time, the biasing assembly 103becomes effective to tension the hose 84. During continued outwardmovement of the inner boom section, the loop 96 rolls along the channel110 against the influence of the springs 142 and 144. This results in arelatively long inner leg 100 of the hose 84 being maintained undertension so that the hose does not whip or deflect sidewardly even thoughthe relatively long inner leg 100 of the hose is not disposed betweenguide walls similar to the guide walls 105 and 106 of the hose trough80. Of course, the slots in the guide walls 104 to 108 could have alength other than the specific length provided in the illustratedembodiment of the invention.

Upon initial retraction of the boom assembly 10 from the position shownin FIG. 7 toward the position shown in FIG. 5, the roller 134 applies abiasing force to the loop 96 to initiate its movement inwardly along thechannel 110 in a direction parallel to the longitudinal axis of theinner and outer boom sections 28 and 30. The loop 96 then continues toroll inwardly along the channel 1 10 between the guide walls 105 and 106under the influence of this biasing force. Since the hose 84 ismaintained under tension by the biasing assembly 103, the hose is notwhipped or flexed sidewardly under the influence of the relatively longinner leg 100 of the hose.

As the boom assembly 10 is retracted, the length of the inner leg 100 ofthe hose 84 decreases and the length of the outer leg 98 increases.Since the outer leg 98 of the hose 84 is located between the guide wallsand 106, the outer leg does not tend to produce a whipping or sidewardmovement of the loop 96. Therefore when the boom assembly 10 has beenretracted to the position shown in FIG. 6, the biasing assembly 103 doesnot have to continue applying tension to the hose 84 to maintain theloop 96 in the channel 110. Accordingly, movement of the axle 136 alongthe channel is interrupted by engagement of the axle with stop surfacesdefining the inner ends of the slots in the walls 104 to 108. Continuedretraction of the boom assembly 10 results in the loop 96 rollingfurther inwardly along the channel 1 l0 and away from the associatedroller 134 of the biasing assembly 103 (FIG. 5). Although therelationship of only the hose 84 to the biasing assembly 103 has beenfully described herein, it should be understood that the hose 86 and anyother conduits in the trough 80 also cooperate with the biasing assembly103 in much the same manner.

The hose trough 80 provides a compact enclosure for both the biasingassembly 103 and the guide arrangement 102. The outer or bottom wall 116of the hose trough 80 extends between end walls 138 and of the cradle 34(FIGS. 2 and 5) and is connected to frame members 46 of the outer boomsection 30 (FIG. 4). The guide walls 104 to 108 are connected at theirouter ends to the bottom wall 116 of the hose trough 80 and extendparallel to each other and to the longitudinal axis of the boom sections28 and 30 to define parallel longitudinally extending channels 109 to112 for receiving flexible conduits, such as the hoses 84 and 86. It iscontemplated that either air hoses or electrical cables will be locatedin the channels 109 and 112 to conduct power to associated apparatuswhich may be mounted on the outer end portion of the inner boom section28. It should be noted that the guide walls 104 and 108 cooperate withthe bottom wall 116 of the hose trough 80 to define a pair oflongitudinally extending channels or chambers 158 and 160 for receivingthe springs 142 and 144.

The conduit arrangement 74 for conducting hydraulic fluid to and fromthe piston and cylinder assembly 70 includes two of the tubular framemembers 50 of the inner boom section 28. Thus, the flexible hose 84 isconnected at 166 (see FIGS. 5 and 6) to the inner end portion of theinner boom section 28. The hollow frame member 50 conducts the hydraulicfluid from the hose connection 166 to a hose connection 170 (FIG. 8)connecting the conduit 90 to the outer end portion of the same tubularframe member 50. The conduit 90 then conducts the hydraulic fluid to thepiston and cylinder assembly 70. The flexible hose 86 (see FIG. 9) isconnected in a similar manner with the conduit 92 (FIG. 8) by anassociated structural member 50 which is located on the opposite side ofthe inner boom section 28. In addition to being fluid conduits, thehollow frame members 50 are important structural components of the innerboom section 28 and are engaged by the rollers 48 (FIG. 8) to supportthe inner boom section for movement relative to the outer boom section30. The hollow structural members 50 also provide support for the tool64 and the piston and cylinder assembly 70. While hydraulic fluid isconducted through the hollow structural members 50 in the specificpreferred embodiment of the invention illustrated herein, it should beunderstood that air or electrical cables could be located within themembers 50.

in view of the foregoing description it can be seen that the boomassembly 10 includes inner and outer boom sections 28 and 30 which aredisposed in a telescopic relationship with each other. The poweractivated apparatus 70 is mounted on the outer end portion of the innerboom section 28 to operate the tool 64. The conduit arrangement 74 isprovided to conduct energy to the power activated apparatus 70. In theillustrated embodiment of the invention, the power activated apparatus70 is a hydraulically actuated piston and cylinder assembly to which theconduit arrangement 74 conducts fluid under pressure. The conduitarrangement 74 includes flexible hoses or conduits 84 and 86 havingloops formed therein which cooperate with guide channels 1 l and l 1 1so that the loops in the flexible conduits 84 and 86 move eitherinwardly or outwardly along these channels in a direction parallel tothe longitudinal axes of the boom sections 28 and 30 when the boomassembly is either extended or retracted. In addition, the biasingassembly 103 is provided to tension the flexible conduits 84 and 86 whenthe boom assembly is in a partially extended condition. This tensioningof the relatively long inner legs of the flexible conduits 84 and 86promotes movement of the loops in the conduits along the guide channels1 l0 and 1 12 in a predetermined manner.

Having described a specific preferred embodiment of the invention, thefollowing is claimed:

1. An extendable and retractable boom assembly comprising a first boomsection, a second boom section mounted in a telescopic relationship withsaid first boom section, said first and second boom sections beingmovable relative to each other to extend and retract said boom assembly,apparatus mounted on said second boom section for movement therewithrelative to said first boom section, conduit means operatively connectedwith said first and second boom sections for conducting energy from asource of energy to said apparatus, guide means connected to said firstboom section and at least partially defining therebetween a channelextending along said first boom section in a direction generallyparallel to a direction of movement of said boom assembly when it isextended or retracted, said conduit means including a flexible portionhaving a loop formed therein with an outer leg of said flexible portionextending from one end of said loop and disposed within said channel andan inner leg of said flexible portion extending from another end of saidloop and operatively connected with said inner boom section in such amanner that the lengths of said legs vary relative to each other andsaid loop moves along said flexible portion and along the channel uponrelative movement between said first and second boom sections duringextension or retraction of said boom assembly, and biasing means forapplying a force to said loop to tension said flexible portion of saidconduit means and to urge said loop to move in a predetermined directionalong said channel upon relative movement between said first and secondsections of said boom assembly.

2. A boom assembly as set forth in claim I wherein said biasing meansincludes roller means disposed within said channel for engaging saidloop and spring means operatively connected to said roller means forurging said roller means in the predetermined direction.

3. A boom assembly as set forth in claim 2 further including stop meansfor arresting movement of said roller means in the predetermineddirection when said loop is in a predetermined position within saidchannel.

4. A boom assembly as set forth in claim 3 wherein said channel extendsin the predetermined direction past said stop means and said loop ismovable along said channel past said stop means and out of engagementwith said roller means upon continued relative movement between saidfirst and second boom sections.

5. A boom assembly as set forth in claim 1 wherein said second boomsection includes a frame means for supporting said apparatus, said framemeans including a hollow member which forms part of said conduit means,said flexible portion of said conduit means and said apparatus beingconnected in fluid communication with said hollow member whereby fluidunder pressure conducted by said conduit means from the source of energycan flow from said flexible portion of said conduit means through saidhollow member in said frame means to said apparatus.

6. A boom assembly as set forth in claim 5 further including rollermeans mounted on said first boom section for at least partiallysupporting said second boom section for movement relative to said firstboom section, said roller means including a roller rotatably mounted onsaid first boom section and disposed in rolling engagement with saidhollow member.

7. A boom assembly as set forth in claim 1 wherein said guide meansincludes a pair of spaced apart side walls with said channel beingformed therebetween and a base wall extending between said side walls,said outer leg of said flexible portion of said fluid conduit meansbeing disposed in abutting engagement with said base wall immediatelyadjacent to said loop.

8. A boom assembly as set forth in claim 7 wherein said biasing meansincludes a roller for engaging said loop, said roller being rotatablymounted on a support member extending between and movable along saidside walls.

9. A boom assembly as set forth in claim I wherein said loop is movableinto and out of engagement with said biasing means as said loop movesalong said channel during extension and retraction of said boomassembly.

10. An extendable and retractable boom assembly comprising a first boomsection, a second boom section mounted in a telescopic relationship withsaid first boom section, said first and second boom sections beingmovable relative to each other to extend and retract said boom assembly,apparatus mounted on said second boom section for movement therewithrelative to said first boom section, conduit means operatively connectedwith said first and second boom sections for conducting energy from asource of energy to said apparatus, said conduit means including aflexible portion having a loo formed therein with an outer leg of saidflexible portion extending from one end of said loop and operativelyconnected with said first boom section and an inner leg of said flexibleportion extending from another end of said loop and operativelyconnected with said inner boom section in such a manner that the lengthsof said legs vary relative to each other and said loop moves along saidflexible portion between a first position in which said outer leg isrelatively long and said inner leg is relatively short and a secondposition in which said outer leg is relatively short and said inner legis relatively long upon relative movement between said first and secondboom sections during extension or retraction of said boom assembly,biasing means for applying a force to said loop when said loop is insaid second position and said inner leg is relatively long to tensionsaid inner leg and maintain said flexible portion of said conduit meansin a desired relationship with said first and second boom sections,means for rendering said biasing means ineffective to apply a force tosaid loop when said loop is in said first position and said inner leg isrelatively short, and guides means for positioning said loop and saidouter leg of said flexible portion of said conduit means in apredetermined relationship with said first boom section when said loopis in said first position.

11. A boom assembly as set forth in claim 10 wherein said biasing meansincludes a roller for engaging said loop and spring means for urgingsaid roller and said loop toward said first position when said loop isin said second position, and said means for rendering said biasing meansineffective including stop means for effecting disengagement of saidroller fr om said loop when said loop is intermediate said first andsecond positions.

12. A boom assembly as set forth in claim 10 wherein said first boomsection includes means for defining a chamber, said outer leg of saidflexible portion of said conduit means and said biasing means beinglocated within said chamber outwardly of said second boom section, saidloop extending inwardly from said chamber to said inner leg which isconnected to said second boom section at a location inwardly of saidchamber and said first boom section.

13. A boom assembly as set forth in claim wherein said guide meansincludes a pair of parallel walls which extend Iongitudinally along saidfirst boom section and guide the movement of said loop as said loopmoves between said first and second positions.

14. An extendable and retractable boom assembly for carrying an externalload, said boom assembly comprising a base, a movable boom sectionoperatively connected with said base and including a longitudinallyextending and load carrying structural member which is hollow, rollermeans operatively connected with said base and having a peripheralsurface disposed in rolling engagement with said hollow structuralmember to at least partially support said boom section for movementbetween a retracted position and an extended position, a fluid operateddevice mounted on an outer end portion of said boom section, and conduitmeans for connecting said fluid operated device in fluid communicationwith a source of fluid under pressure, said fluid conduit meansincluding said hollow structural member and means for connecting theinterior of said hollow structural member in fluid communication withsaid source of fluid under pressure and means for connecting theinterior of said hollow structural member in fluid communication withsaid fluid operated device to enable fluid to flow from said source offluid through said hollow structural member to said fluid operateddevice, said means for connecting the interior of said hollow structuralmember in fluid communication with said source of fluid under pressureincluding a flexible conduit a first end portion of which is connectedwith said boom section and a second end portion of which is connectedwith said source of fluid, said flexible fluid conduit having a loopformed therein intermediate said first and second end portions so thatthe lengths of said first and second end portions vary relative to eachother and said loop moves along said flexible conduit upon movement ofsaid boom section during extension and retraction of said boom assembly.

15. A boom assembly as set forth in claim 14 further including biasingmeans for engaging said loop and applying a force thereto to tensionsaid flexible conduit and urge said loop in a predetermined directionupon movement of said boom section.

16. An extendable and retractable boom assembly comprising a first boomsection, a second boom section mounted in a telescopic relationship withsaid first boom section, said first and second boom sections beingmovable relative to each other to extend and retract said boom assembly,apparatus mounted on said second boom section for movement therewithrelative to said first boom section, conduit means operatively connectedwith said first and second boom sections for conducting energy from asource of energy to said apparatus, said conduit means including aflexible portion having a loop formed therein with an outer leg of saidflexible portion extending from one end of said loop and operativelyconnected with said first boom section and an inner leg of said flexibleportion extending from another end of said loop and operativelyconnected with said inner boom section in such a manner that the lengthsof said legs vary relative to each other and said loop moves along saidflexible portion between a first position in which said outer leg isrelatively short and a second position in which said outer leg isrelatively short and said inner leg is relatively long upon relativemovement between said first and second boom sections during extension orretraction of said boom assembly, biasing means for applying a force tosaid loop when said loop is in said second position and said inner legis relatively long to tension said inner leg and maintain said flexibleportion of said conduit means in a desired relationship with said firstand second boom sections, said biasing means including a roller forengaging said loop and spring means for urging said roller and said looptoward said first position when said loop is in said second position,and means for rendering said biasing means ineffective to apply a forceto said loop when said loop is in said first position and said inner legis relatively short, said means for rendering said biasing meansineffective including stop means for effecting disengagement of saidroller from said loop when said loop is intermediate said first andsecond positions.

1. An extendable and retractable boom assembly comprising a first boomsection, a second boom section mounted in a telescopic relationship withsaid first boom section, said first and second boom sections beingmovable relative to each other to extend and retract said boom assembly,apparatus mounted on said second boom section for movement therewithrelative to said first boom section, conduit means operatively connectedwith said first and second boom sections for conducting energy from asource of energy to said apparatus, guide means connected to said firstboom section and at least partially defining therebetween a channelextending along said first boom section in a direction generallyparallel to a direction of movement of said boom assembly when it isextended or retracted, said conduit means including a flexible portionhaving a loop formed therein with an outer leg of said flexible portionextending from one end of said loop and disposed within said channel andan inner leg of said flexible portion extending from another end of saidloop and operatively connected with said inner boom section in such amanner that the lengths of said legs vary relative to each other andsaid loop moves along said flexible portion and along the channel uponrelative movement between said first and second boom sections duringextension or retraction of said boom assembly, and biasing means forapplying a force to said loop to tension said flexible portion of saidconduit means and to urge said loop to move in a predetermined directionalong said channel upon relative movement between said first and secondsections of said boom assembly.
 2. A boom assembly as set forth in claim1 wherein said biasing means includes roller means disposed within saidchannel for engaging said loop and spring means operatively connected tosaid roller means for urging said roller means in the predetermineddirection.
 3. A boom assembly as set forth in claim 2 further includingstop means for arresting movement of said roller means in thepredetermined direction when said loop is in a predetermined positionwithin said channel.
 4. A boom assembly as set forth in claim 3 whereinsaid channel extends in the predetermined direction past said stop meansand said loop is movable along said channel past said stop means and outof engagement with said roller means upon continued relative movementbetween said first and second boom sections.
 5. A boom assembly as setforth in claim 1 wherein said second boom section includes a frame meansfor supporting said apparatus, said frame means including a hollowmember which forms part of said conduit means, said flexible portion ofsaid conduit means and said apparatus being connected in fluidcommunication with said hollow member whereby fluid under pressureconducted by said conduit means from the source of energy can flow fromsaid flexible portion of said conduit means through said hollow memberin said frame means to said apparatus.
 6. A boom assembly as set forthin claim 5 further including roller means mounted on said first boomsection for at least partially supporting said second boom section formovement relative to said first boom section, said roller meansincluding a roller rotatably mounted on said first boom section anddisposed in rolling engagement with said hollow member.
 7. A boomassembly as set forth in claim 1 wherein said guide means includes apair of spaced apart side walls with said channel being formedtherebetween and a base wall extending between said side walls, saidouter leg of said flexible portion of said fluid conduit means beingdisposed in abutting engagement with said base wall immediately adjacentto said loop.
 8. A boom assembly as set forth iN claim 7 wherein saidbiasing means includes a roller for engaging said loop, said rollerbeing rotatably mounted on a support member extending between andmovable along said side walls.
 9. A boom assembly as set forth in claim1 wherein said loop is movable into and out of engagement with saidbiasing means as said loop moves along said channel during extension andretraction of said boom assembly.
 10. An extendable and retractable boomassembly comprising a first boom section, a second boom section mountedin a telescopic relationship with said first boom section, said firstand second boom sections being movable relative to each other to extendand retract said boom assembly, apparatus mounted on said second boomsection for movement therewith relative to said first boom section,conduit means operatively connected with said first and second boomsections for conducting energy from a source of energy to saidapparatus, said conduit means including a flexible portion having a loopformed therein with an outer leg of said flexible portion extending fromone end of said loop and operatively connected with said first boomsection and an inner leg of said flexible portion extending from anotherend of said loop and operatively connected with said inner boom sectionin such a manner that the lengths of said legs vary relative to eachother and said loop moves along said flexible portion between a firstposition in which said outer leg is relatively long and said inner legis relatively short and a second position in which said outer leg isrelatively short and said inner leg is relatively long upon relativemovement between said first and second boom sections during extension orretraction of said boom assembly, biasing means for applying a force tosaid loop when said loop is in said second position and said inner legis relatively long to tension said inner leg and maintain said flexibleportion of said conduit means in a desired relationship with said firstand second boom sections, means for rendering said biasing meansineffective to apply a force to said loop when said loop is in saidfirst position and said inner leg is relatively short, and guides meansfor positioning said loop and said outer leg of said flexible portion ofsaid conduit means in a predetermined relationship with said first boomsection when said loop is in said first position.
 11. A boom assembly asset forth in claim 10 wherein said biasing means includes a roller forengaging said loop and spring means for urging said roller and said looptoward said first position when said loop is in said second position,and said means for rendering said biasing means ineffective includingstop means for effecting disengagement of said roller from said loopwhen said loop is intermediate said first and second positions.
 12. Aboom assembly as set forth in claim 10 wherein said first boom sectionincludes means for defining a chamber, said outer leg of said flexibleportion of said conduit means and said biasing means being locatedwithin said chamber outwardly of said second boom section, said loopextending inwardly from said chamber to said inner leg which isconnected to said second boom section at a location inwardly of saidchamber and said first boom section.
 13. A boom assembly as set forth inclaim 10 wherein said guide means includes a pair of parallel wallswhich extend longitudinally along said first boom section and guide themovement of said loop as said loop moves between said first and secondpositions.
 14. An extendable and retractable boom assembly for carryingan external load, said boom assembly comprising a base, a movable boomsection operatively connected with said base and including alongitudinally extending and load carrying structural member which ishollow, roller means operatively connected with said base and having aperipheral surface disposed in rolling engagement with said hollowstructural member to at least partially support said boom section formovement between a retracted position and an extended position, a fluidoperated device mounted on an outer end portion of said boom section,and conduit means for connecting said fluid operated device in fluidcommunication with a source of fluid under pressure, said fluid conduitmeans including said hollow structural member and means for connectingthe interior of said hollow structural member in fluid communicationwith said source of fluid under pressure and means for connecting theinterior of said hollow structural member in fluid communication withsaid fluid operated device to enable fluid to flow from said source offluid through said hollow structural member to said fluid operateddevice, said means for connecting the interior of said hollow structuralmember in fluid communication with said source of fluid under pressureincluding a flexible conduit a first end portion of which is connectedwith said boom section and a second end portion of which is connectedwith said source of fluid, said flexible fluid conduit having a loopformed therein intermediate said first and second end portions so thatthe lengths of said first and second end portions vary relative to eachother and said loop moves along said flexible conduit upon movement ofsaid boom section during extension and retraction of said boom assembly.15. A boom assembly as set forth in claim 14 further including biasingmeans for engaging said loop and applying a force thereto to tensionsaid flexible conduit and urge said loop in a predetermined directionupon movement of said boom section.
 16. An extendable and retractableboom assembly comprising a first boom section, a second boom sectionmounted in a telescopic relationship with said first boom section, saidfirst and second boom sections being movable relative to each other toextend and retract said boom assembly, apparatus mounted on said secondboom section for movement therewith relative to said first boom section,conduit means operatively connected with said first and second boomsections for conducting energy from a source of energy to saidapparatus, said conduit means including a flexible portion having a loopformed therein with an outer leg of said flexible portion extending fromone end of said loop and operatively connected with said first boomsection and an inner leg of said flexible portion extending from anotherend of said loop and operatively connected with said inner boom sectionin such a manner that the lengths of said legs vary relative to eachother and said loop moves along said flexible portion between a firstposition in which said outer leg is relatively short and a secondposition in which said outer leg is relatively short and said inner legis relatively long upon relative movement between said first and secondboom sections during extension or retraction of said boom assembly,biasing means for applying a force to said loop when said loop is insaid second position and said inner leg is relatively long to tensionsaid inner leg and maintain said flexible portion of said conduit meansin a desired relationship with said first and second boom sections, saidbiasing means including a roller for engaging said loop and spring meansfor urging said roller and said loop toward said first position whensaid loop is in said second position, and means for rendering saidbiasing means ineffective to apply a force to said loop when said loopis in said first position and said inner leg is relatively short, saidmeans for rendering said biasing means ineffective including stop meansfor effecting disengagement of said roller from said loop when said loopis intermediate said first and second positions.